1. Satellite trajectory: There are 24 GPS satellites orbiting the earth along six orbits (every four groups). Generally, there are no more than 12 satellites on the same side of the earth. Most GPS receivers can track 8 to 12 satellite. At least 3 satellites are required to calculate the LAT/LONG (2D) coordinates. Add one more to calculate the 3D coordinates. For a given location, the GPS receiver knows which satellites are nearby at this time because it constantly receives updates from the satellite.
This article refers to the address: http://
2, parallel channel: Some consumer GPS devices have 2 to 5 parallel channels to receive satellite signals. Since up to 12 satellites are visible (average is 8), this means that the GPS receiver must access each satellite in sequence to obtain information for each satellite. Most of the GPS receivers on the market are 20-parallel channel type, which allows them to continuously track the information of each satellite. The advantages of the 12-channel receiver include fast cold start and initialization of satellite information, and there can be more in the forest area. Good reception. A typical 20-channel receiver does not require an external antenna unless you are in an enclosed space, such as a cabin or a car.
3. Positioning time: This refers to the time it takes to determine the current position when you restart your GPS receiver. For a 20-channel receiver, if you are near the last positioning position, the positioning time for cold start is generally 3 to 5 minutes, and for hot start is 15 to 30 seconds.
4, positioning accuracy: The positioning accuracy of the horizontal position of most GPS receivers is about 2.93m ~ 29.3m.
5, DGPS function: In order to minimize the impact of SA and atmospheric refraction, there is a device called DGPS transmitter. It is a fixed GPS receiver (set in a radius of 100km to 200km on an exploration site) to receive satellite signals. It knows exactly what the precise time the satellite signal is theoretically transmitted, and then compares it with the actual transmission time. Compare and then calculate the "difference", which is very close to the effect of SA and atmospheric refraction, which sends this difference and other GPS receivers can use it to get a more accurate position reading (5m ~ 10m or less) Error). Many GPS equipment providers have set up DGPS transmitters in some areas for their customers to use for free, as long as the GPS receivers purchased by customers have DGPS capabilities.
6. Signal interference: To give you a good positioning, the GPS receiver needs at least 3 to 5 satellites to be visible. If you are in a canyon or on a street lined up in two high-rise buildings, or in a dense jungle, you may not be able to contact enough satellites to locate or only get two-dimensional coordinates. Similarly, if you are in a building, you may not be able to update your location, some GPS receivers have separate antennas that can be attached to the windshield, or an external antenna can be placed on the roof, which will help you The receiver gets more satellite signals.
7. Physical indicators: When purchasing GPS equipment, physical indicators such as size, weight, display screen, waterproof, shockproof, dustproof performance, high temperature resistance, and power consumption must be taken into account.
Silent Diesel Gensets, 3000KW Diesel Generators, 4000KW Diesel Generators,4000KW Silent Diesel Genset
Jinan Guohua Green Power Equipment Co.,Ltd. , https://www.guohuagenerator.com